1. Field of the Invention
The present invention relates to a cellular terminal apparatus such as a collapsible cellular telephone and in particular, to a water-proof cellular terminal apparatus.
2. Description of the Prior Art
Conventionally, various water-proof countermeasures have been tried for the respective components of the apparatus such as a cellular telephone.
For example, Japanese Patent Laid-Open Application 2000-151772 discloses a cellular terminal apparatus having a water-proof structure against entrance of water from the peripheral portion of the key sheet as the operation unit. Moreover, Japanese Patent Laid-Open Application 10-169780 discloses a seal packing and its manufacturing method. The seal packing can preferably be used as a water-proof countermeasure against the water entrance from the engagement portion of the upper and the lower cases of the cellular terminal apparatus.
Moreover, there is a completely water-proof cellular telephone (unitary block type) having a countermeasure against water coming through a hole (sound hole, etc.) and other clearances. However, a collapsible cellular telephone, i.e., a collapsible type cellular telephone in which an upper apparatus and a lower apparatus can be folded via a hinge portion, has become more popular and there are a lot of market claims (complaint, indication, etc.) for the water entrance from the clearance at the hinge portion.
More specifically, water enters from the clearance at the hinge portion into the FPC (flexible printed circuit) arranged in the hinge portion and along the FPC reaches the printed circuit board in the upper and lower apparatuses, causing electrical problems. Here, the FPC has flexibility and is used to connect the printed circuit boards arranged in the upper and the lower apparatuses.
FIG. 8 and FIG. 9 show a configuration example of a cellular telephone having a countermeasure against the water entrance (there is a possibility of entrance of dust other than water) from the hinge portion clearance. FIG.8 is a front view of the cellular telephone (the case is open) and a cross section about III-III is shown in FIG. 9.
In the configuration shown in FIG. 8 and FIG. 9, the space between the hinge portion 4 and the upper and lower apparatuses (upper apparatus 2, lower apparatus 3) is supplied with a seal packing P which sandwiches from upside and downside, apart of the FPC 7 as a route of water entrance into the upper and lower apparatuses 2 and 3, so that no space is left between the FPC 7 and the external case of the FPC 7. Since the seal packing mounts in the space, the FPC 7 is in pressed contact with the seal packing P. Moreover, the seal packing is in pressed contact with the case. Thus, there is no water entrance route from the hinge portion 4 to the upper and lower apparatuses 2 and 3, thereby achieving water-proof structure.
However, among the collapsible cellular telephones, there are those having a structure that a coaxial cable and the like are arranged in the hinge portion 4. The FPC 7 connecting the upper and the lower printed circuit boards 5 and 6. FIG. 10 and FIG. 11 show a configuration example of the cellular telephone in which the FPC and the cable are arranged in the hinge portion and water-proof structure using the aforementioned seal packing is provided. FIG. 10(a) is a front view of the cellular telephone and FIG. 10(b) is a rear view of the cellular telephone. FIG. 11 is a cross sectional view about IV-IV in FIG. 10(b).
As shown in FIG. 10 and FIG. 11, the connection cable (coaxial cable) 8 passes through the hinge portion 4 together with the FPC 7 and is connected to the upper and the lower printed circuit boards 5 and 6. The spaces at the boundaries between the hinge portion 4 and the upper and lower apparatuses 2, 3 are supplied with a seal packing P (four seal packing pieces are arranged in the figure) The FPC 7 and the cable 8 pass between the seal packing P pieces in the direction of the upper and the lower apparatuses 2, 3. Thus, the spaces are minimized by the seal packing P pieces so as to prevent entrance of water drops in the direction of the upper and the lower apparatuses 2, 3.
FIG. 12(a) and FIG. 12(b) shows a water-proof structure having two seal packing P pieces which sandwich the FPC 7 and the cable 8 from upside and downside. The FPC 7 is in pressed contact with the seal packing P so as to prevent entrance of water drops. The seal packing P is also in pressed contact with the external case. Moreover, the cable 8 passes through a surface where the seal packing P is in pressed contact with the FPC 7.
In the water-proof structure shown in FIG. 12(a), the FPC 7 and the cable 8 are sandwiched by the seal packing P at separate positions. In the water-proof structure shown in FIG. 12(b), the FPC 7 and the cable 8 are sandwiched together (the cable 8 is arranged on the upper surface of the FPC 7) by the seal packing P.
In the aforementioned configuration, a space S is present around the cable 8 covered by the seal packing P. Through this space S, a water drop 11 (see FIG. 9, FIG. 11) enters inside and along the FPC 7 or the cable 8, reaches the printed circuit boards 5, 6 in the upper and lower apparatuses 2, 3, thereby causing electric problems (such as short circuit).
Moreover, especially in the configuration of 12(b) where the cable 8 passes through a portion where the seal packing P is pressed contact with the FPC 7, an excessive load is applied to the FPC 7 and the cable 8 (especially onto the FPC 7). This causes a problem that the signal line in the FPC 7 is broken.
As has been described above, in the conventional configuration, no consideration has been taken on an appropriate water-proof structure for the configuration of the hinge portion passing the FPC and the connection cable.